Recently, lighting devices have been developed utilizing light emitting diodes (LEDs) for a variety of lighting applications. Due to the increasing use of LEDs for lighting applications, LED lamps are developed to replace common incandescent or fluorescent lamps, i.e. for retrofit applications. In addition to an increase in the lifetime of such LED lamps in comparison to common lamps and thus lower cost, LED lamps typically contain less hazardous materials, so that recycling processes of such lamps can be conducted more efficiently.
For the above mentioned retrofit applications, the LED lamp typically is adapted to fit the socket of the respective fixture to be retrofitted. Furthermore, since a maintenance of a lamp typically is conducted by a user, the LED lamp should be readily operational with any type of suitable fixture without the necessity of an elaborate modification of the fixture.
LEDs typically exhibit a higher luminous efficacy than common light sources and thus draw less current from the power supply for a given luminous flux. While this fact is advantageous for the present efforts for energy conservation, difficulties might arise when retrofitting a fixture which is designed for a nominal power. Depending on the circuit design of the fixture, the differing current draw may result in significant electrical problems, such as overheating of the ballast or an inacceptably low power factor when operating a LED lamp with such fixture.
Therefore, it is an object of the present invention to provide an LED retrofit lamp for operation with an alternating current which may be manufactured cost-efficiently and allows a versatile and optimized operation, in particular with common types of fixtures.